This invention relates to a method for controlling the migration and removal of gas bubbles and voids from a metal material.
Nuclear reactor lifetimes are influenced by the structural damage due to gas bubbles and voids. The formation and growth of helium bubbles in metals and alloys following (n,.alpha.) reactions or .alpha. implantation are of practical interest due to the long-term deleterious effects of inert gases in fission and fusion reactor structural materials, such as reactor fuel cladding or containment structural materials. Because inert gas atoms are essentially insoluble in all metals, bubbles quickly nucleate at defects in the host lattice and subsequently grow by acquisition of additional gas atoms (and capture of vacancies to lower the gas pressure within the bubble) and by bubble migration and coalescence. In multiphase alloys, inert gas bubbles are typically found at matrix/precipitate interfaces.
It is an object of this invention to provide a process whereby inert gas bubbles and voids are removed from fusion and fission reactor materials.
It is another object of this invention to provide a process whereby impurity metal particles attached to the bubbles or voids are melted to provide a liquid coating to allow the bubble or void to migrate with much greater velocity than is otherwise possible.
It is still a further object of this invention to provide a process for biasing the direction of migration of the bubble or void out of a metal by applying a temperature gradient across the metal.
Additional objects, advantages and novel features of the invention will become apparent to those skilled in the art upon examination of the following and by practice of the invention.